Lock-stitch sewing machine



' Aug. 4, 1925.

WlTNE E5 M. HEMLEB LOCK STITCH SEWING MACHINE Filed July 16, 1923 5 Sheets-Sheet 1 INVENTOR Aug. 4, 1925. 1 1,548,464

M. HEMLEB LOCK STITCH SEWING MACHINE File July 16, 1923 5 Sheets-Sheet 2 1 Q '1 :16 .aa e4 m 'i l V INVENTOR 8 fitmLI/W lml sgs Aug. 4, 1925.

M. HEMLEB LOCK STITCH SEWING MACHINE 5 Shets-Sheet 3 Filed July INVENTOR (;'/W

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M. HEMLEB LOCK STITCH SEWING MACHINE Filed July 16 5 Sheets-Sheet 4 INVENTOR fizmtw/M ATTORNEY M. HEMLEB LOCK STITCH SEWING MACHINE Aug. 4, 1925.

Filed July 16, 1923 5 Sheets Sheet 5 M V 'l k INVENTOR fizuzzm By ATTORNEY Patented Aug. 4, 1925.

UNITED STATES MARTIN HEMLEB, 0F ELIZABETH, NEW JERSEY, ASSIGNO'R TO THE SINGER MANU- FAGTURING COMPANY, OF ELIZABETH, NEW JERSEY, A CORPORATION OF NEW JERSEY.

LOGKSTITCH SEWING MACHINE.

Application filed July 16, 1923. Serial No. 651,800.

To all whom it may concern:

Be it known that I, MARTIN HEMLEB, a citizen of the United States, residing at Elizabeth, in the county of Union and State of NewJerseyfhave invented certain new and useful Improvements in Lock-Stitch Sewing Machines, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to lock-stitch sewing machines, more particularly of the rotary hook type. Machines of the type in question have been constructed to sew satisfactorily and without tendency to overheat at speeds of from 3500 to 4000*stitches per minute but have had a bobbin capacity limited to about 75 yards of No. 90 cotton. WVith such machines, however, it is neces} sary to manually adjust the take-up to'suit the thickness of work to be sewed, and even with this adjustment the machine is only able to sew' work Varying from thin to medium thickness.

In all prior lock-stitch machines with which I am familiar, conditions are such that there is a delay in the take-up action upon the needle-loop, considerable slack remaining in such loop as the needle starts down. I This delay is largely responsible for chafing of the needle-thread by the point of the needle which, under the conditions noted, is descending simultaneously with the ascent of the needle-thread pulled from the'needle-loop by the take-up. Since'the take-up must finish its take-up action and give slack for the needle-eye ,to .double through the work, it follows that a delayed take-up action necessitates a delayed slack giving action and hence it has been necessary to delay the time when the needleeye reaches the work by increasing the stroke of the needle-bar above the work. Such increase in the stroke of the needlebar increases vibration, reduces the speed at which the machine can be satisfactorily operated and increases the distance between the needle-eye and the work during the take up action, thus increasing the danger of the upwardly moving needle-thread whipping or vibrating laterally sufliciently to be caught or chafed by the needle-point.

The present invention has for an object to effect a material increase. in the bobbin ca pacity of a lock-stit ch sewing machine without a sacrifice of desirable high-speed operating characteristics.

Another object of the invention is to pr0- .vide a machine which will sew work of greater variation in thickness than has heretofore been considered feasible at speeds of from 3500 to 4000 stitches per minute, and which will sew from the thinnest to the thickest work (a range of about five-sixteenths of an inch) .at these speeds without manual adjustment.

Another object of the invention is to provide a rotary hook sewing machine havmg the parts so combined and related as to complete the taking up of the slack in the needle-1oop after it has been cast about the bobbin and before the needle begins its down stroke, thereby minimizing the danger of the needle-point chafing the thread and ellecting substantially the complete take up of the needle-loop during the latter part of the up-stroke of the needle with the consequent important advantage of being able to sew work of maximum thickness with a minimum needle-stroke.

Another object of the invention is to provide improved and simplified means facilitating the removal and replacement of the bobbin without necessitating breakage or disturbance of the needle-thread, or interruption of the seam at the upper side ofthe work.

Another object of the invention is to provide improved means for controlling the.

needle-loop so that it may be freely drawn up without twisting or kinking during the latter part of its passage about the bobbin.

A further object of the invention is to provide for the easy threading of the bobbin-case and also to guard the under thread against seizure by the rotary hook on an idle rotation.

Still further, the invention has for an object to guard against second looping or seizure of the needle-thread by the hook on an idle rotation.

Further objects of the invention will appear from the following description and claims. v

I have found by experimentation that by combining a crank-and-link operated takeup with a rotary hook making three revolutions. for each complete reciprocation of the needle-bar, I am enabled to effect the by the take-up, it follows that I am thus enabled to sew work up to a maximum thickness with a minimum needle-bar stroke, which latter is an important desideratum of a high-speed machine.

In order to avoid the speed-limiting factor of frictional over-heating encountered when a bobbin-case is supported by and in a raceway in a circularly moving hook and also to avoid the necessity of lubrication of the hook raceway with its attendant liability to soil the thread, I prefer to han'g the bobbin-case within the field of action of the hook from a stationary support; the hook having an open-sided raceway which assists in retaining the bobbin-case 1n operative position but does not bear the weight of the bobbin-case.

Heretofore, in machines having a hook of the open-sided raceway type and a bobbincase supported independently of the hook, the pull on the bobbin-thread during the feed of the work has been depended upon to lift the bobbin-case from its support to afford a gap for passage of the needle-loop as the latter is being drawn up to the work. With small and light bobbin-cases, such as heretofore used, the lifting action occasioned by the upward pull on the bobbinthread appears to have been satisfactory. A material increase'in the capacity of .the bobbin, however, such as herein contemplated, increases the Weight of the assembled bobbin and bobbin-case, making it impracticable to depend upon the pull of the bobbin-thread during the feed to lift the bobbin-case assembly; it being remembered that the present machine is intended to sew at speeds exceeding 3500 stitches per minute, necessitatingan equally rapid intermittent lifting of the bobbin-case.

In order to permit of the contemplated material increase in the capacity of the bobbin and to insure free passage of the needleloop between the bobbin-case and its stationary support, I provide means for engaging and lifting the bobbin-case from its support at the desired time during each stitch-forming cycle, such means being out of engagement with the bobbin-case at another stage of the stitch-forming cycle so that the needle-loop can pass between the bobbin-case and such means.

In order to facilitate removal and replacement of the bobbin-case without necessitating disturbance of the needle-thread or interruption of the seam at the upper side of the work, I provide the bobbin case support, which may be swung outwardly away from the hook, with means for seizing the bobbin-case and pulling it out of the hook; the bobbin-case being forced to more with its-support to open position where it is fully exposed and may be readily seized between the operators thumb and fore-finger and removed from the machine for replenish ment of the under thread mass. The forcible removal of the bobbin-case from its operative position within the hook to a predetermined position out of the hook also serves to pull off a predetermined length of bobbin-thread which is positioned accessibly for ready severance by the operator prior to picking up the bobbin-case.

To secure the free and easy passage of the needle-loop between the bobbin-case and its rotation restraining means in a high speed rotary hook machine and to prevent twisting and kinking of the needle-loop are matters requiring the utmost nicety of treatment. In the present instance the desired results are secured by providing the bobbincase with a slightly undercut loop-detaining horn adjacent that side of the usual rotation restraining notch last passed by the hookbeak. This provision causes the supply-limb of the loop being drawn up to approach and pass through the rotation-restraining notch in the same direction in which the hook is travelling; the work-limb of such loop being detained by said horn until the supply-limb has passed through the rotation-restraining notch and until the loop has been reduced to a small size free from twists or kinks.

The loop detaining horn operates to guide and control the needle-loop until the latter is finally drawn off'of said horn when it is of such small size that it can safely traverse the remaining short distance up to the Work unassisted.

Easy threading of the bobbin-case is provided for by omitting all closed threadeyes and by arranging for the passage of the bobbin thread across the onter end face of the bobbin-case from the usual tension spring to and upwardly through the rotation-restraining notch. The'bobbin-case is formed with a thin ledge extending partially across and forming a bottom wall in the rotationrestraining notch serving to guard the bobbin-thread against seizure by the hook. With the present construction it is merely necessary to draw the bobbin-thread under the tension spring prior to insertion of the bobbin-case in the hook. The first needleloop cast about the bobbin-case automatically draws the bobbin-thread into the rotation-restraining notch and in position .against the guarding ledge, thus completing the hook until the supply-limb of the needleloop has escaped upwardy through the oblique slot in the hook-body, alongside the hook-beak, and is safely out of range of said beak. This flange is also provided with a cam-edge so located as to dislodge the needle-loop from the loop-detaining heel of the hook immediately after escape of the supply-limb of such loop through the said oblique slot.

- The invention further comprises certain details of construction and combinations of parts hereinafter referred to.

In the accompanying drawings, Fig. 1 is a longitudinal vertical section through the frame of a sewing machine embodying the invention. Figs. 2 and 3 are perspective views of the rotary hook shown in Fig. 1. Fig. 4 is a side elevation of the hook and bobbin-case assembly on an enlarged scale. Fig. 5 is a top plan view of the hook and bobbin-case assembly. Fig. 6 is a section on the line 6, 6, Fig. 5. Fig. 7 is a disassembled perspective view of the bobbin-case support. Fig. 8 is. a rear side elevation of the bobbin-case support. Fig. 9 is an inner face View of the bobbin-case, support. Figs. 10, 11 and 12 are, respectively, top plan, outer face and inner face views of the bobbin-case. Fig. 10* is a section on the line 10 10, Fig. 11. Fig. 13 is a section on the line'13, 13,Fig. 11. 'Figs. 14 and 15 are, respectively, front and rear side elevations of the bobbin-case. Figs. 16, 17 and 18 are perspective views of the bobbincase in difierent positions. Fig. 19 is a perspective view of the bobbin-retaining device. Fig. 20 is a longitudinal section through said device. Fig. 21 is a perspective view of the expandin screw which is threaded into the end of t e device shown in Figs. 19 and 20. Figs. 22 to 27, inclusive, illustrate successive stages of the passage ofa needle-loop about the bobbin-case. Fig. 28 is a perspective view of the parts in the position shown in Fig. 24. Fig. 29 il lustratcs the relative positions of the needlebar and link take-up at the beginning of the take-up action. Fig. 30 illustrates the relative positions of the needle-bar and take-up when the needle-loop has been drawn up to the work. Fig. '31 illustrates the take-up ready to give slack early in the down-stroke of the needle-bar.

In the embodiment of the invention illustrated, 1 represents the bed-plate ofa sewing machine from which rises the standard '2 of the bracket-arm 3 terminating in the head 4. The main-shaft 5 is journaled in the arm 3 and at its forward end carries the needle-bar and take-up operating cranks 6,

7, respectively, which, in accordance with the present improvement, are set quite close together; the radius of movement of the needle-bar crank being smaller than that of the take-up crank. The needlebar crank 6 is connected by means of the usual link 8 to the needle-bar 9 which carries the eyepoihted neeedle 10.

The main-shaft 5 carries the usual. balance-wheel 11 and has secured thereto the bevel-gear 12 which meshes with the gear 13 on the upper end of the vertical shaft 14 carrying at its lower end the bevel gear 15 which meshes with the gear 16 on the hookshaft 17 journaled in bearings 18 below the bed 1. The gear-ratios are so chosen that the hook-shaft 17 is given three rotations to one rotation of the main-shaft 5. The bearings 18 are preferably constructed in accordance with the disclosure of my copending application Serial No. 651,802,.filed herewith.

The feeding mechanism is preferably constructed in accordance with the disclosure of my copending application Serial No. 651,801, filed herewith. Such feeding mechanism comprises the. feed-lift eccentric 19 and feed-advancing eccentric 20 which, through the pitmen 21,22 operate the feedlift rock-shaft 23 and feed-advancing rockshaft 24. The feed-lift rock-shaft 23 has fixed thereto the L-shaped arm 25, Fig. 22, formed at its free end with a socket for reception of the lower spherical end of a pin 26 the upper spherical end of which is sock eted in the forward end of the feed-bar 27 pivotally connected at 28 to the feed rockerarm 29 fixed to the feed-advancing'rockshaft 24. The spring 30 holds the feed-bar 27 and arm 25 in contact with the opposite ends of the pin 26 at all times. Mounted shoulder 38. Bridging the gap 35 on the.

outside of the hook-body is the usual plate 39 which except at its opposite ends is spaced-from the outer wall of the hookbody, as shown in Figs. 5 and 6. The outer edge 40 of the plate 39 is concaved and spaced from the adjacent transversely convexed surface 41, Fig; 6, of the hookbeak 36. The concaved edge of the plate 39 engages the work-limb of the needle-loop seized by the hook-beak 36 and deflects such limb outwardly so that it will pass across the outer face of the bobbin-case. The rizn of the hook-body is notched adjacent the trailing end of the bridge-plate 39 to form the loop-arresting heel 42.

The bobbin-case is adapted to be supported Within the open raceway of the hook without resting upon the latter. It is formed with a cylindrical body 43 having at one end the diametrically extending web support 44 for the axially disposed tubular bobbin-supporting pin 45 in which is secured a split bobbin-retaining device 46. Referring to Figs. 19, 20 and 21, it will be understood that the bobbin-retaining device 46 is in the form of a sleeve slotted longitudinally throughout its length at 47 to permit expansion of such sleeve within the tube 45 under the influence of the taper-headed screw 48. The sleeve 46 is provided with three additional slots. 49 which, however, do

"not extend the entire length of the sleeve but terminate adjacent the socket for the screw 48. The slots 47, 49, define resilient tongues 50 the outer ends of which are taper-flanged outwardly and extend slightly beyond the outer surface of the sleeve 45, thus constituting yielding retaining means for the bobbin 51, Fig. 6. Pressure exerted upon the bobbin will compress the resilient tongues 50 sufiiciently to release the bobbin and permit-it to slip off the free end of the tube 45.

The bobbin-case is formed with the rotation-restraining notch 52 and with a peripheral flange formed in three sections 53, 53 and 53, which are received in the hookraceway 37 with the usual clearance for the free passage of the needle-loop and a limited up and down motion of the bobbincase. The upper end of the section 53? is formed with an abrupt oblique shoulder constituting the usual stationary hook 54 which arrests the portion of the needleloop beneath the hook-beak while such loop 18 being given a half twist and passed around the bobbin-case in the usual manner well understood by those familiar with the operation of rotary hook machines. The upper end of the flange section 53 presents a shoulder 55 which, during the latter portion of the loop-casting operation, or as the take-up is drawing up the needle-loop, prevents escape of the supply-limb of the needle-loop until the loop-releasing shoulder 38 of the hookracewaypa'sses the shoulder 55.

Mounted on the bobbin-case between the flange sections 53 and 53 is the usual tension spring 56 which bears upon the bobbinthread extending along the outer surface of the bobbin-case between the inner ends of the threading slots 57, 58.

Extending outwardly from the flange section 53 is the guard flange 59 which covers the hook-point during the latter portion of -with a narrow ledge 60, Fig. 11, which extends partially'across the space between the walls 52 of the rotation-restraining notch and guards the bobbin-thread against seizure by the rotary hook. The bobbin-thread lays in the corner formed at the juncture of the ledge 60 and the adjacent or left-hand wall of the notch 52, Fig. 10. The needle 10, Fig. 10, descends in the space between the ledge 60 and the opposite wall 52.

The bobbin-case is provided, on that side of the rotation-restraining notch last passed by the hook-beak with a loop-detainin horn 61 the base of which is slightly recessed in one corner of its outer face at 62 to detain the work-limb of the needle-loop until the supply-limb has been drawn through the rotation-restraining notch 52.

In order to support the bobbin-case so that its weight is not borne by the rotary hook, it is formed with the hanger flan '63, 68, which rest upon the upper circu ar edge-portion of the bobbin-case supporting disk 64, the axial stem 65 of which, Figs. 8 and 9, is fixed by means of the screw 68 in the vertical arm 66 of the swin ing bobbin-case supporting bracket 67. he screw 68 passes through a clearance hole 68' in the bracket 66 and is threaded into the stem 65; the hole 68 being large enough to permit a limited longitudinal adjustment of .the stem 65 in the bracket 66.

The bobbin-case is formed diametrically opposite the rotation-restraining notch 52 with a surface 69 which is raised slightly above the surface of the web 44 and the adjacent edge portions of the bobbin-case body, This surface 69 rests lightly against the face of the bobbincase supporting disk 64 and.

The adjustment is effected by means of the the screw 75 is turned, thus raising or lowering thefree end 71 and altering the extent to which the bobbin-case is lifted. The adjustment shouldbe so made that the hanger flanges 63, 63 will be lifted off of the bobbin-case supporting disk.64 sufiiciently to afford a gap for the free passage of the needle-loop, but not so far as to cause jamming or harsh contact .of the bobbin-case within the rotary hook.

When the bobin-case is hanging from its supporting disk 64, the rotation-restraining notch 52 is'entered by the fixed and movablejaws 76, 77 of an expansible bobbincase removing device. While the machine is sewing, these jaws merely constitute a rotation-restraining tongue which loosely enters the notch 52 in the bobbin-case. The fixed jaw 76 is rigidly mounted on the disk 64. The movable jaw is. formed at the upper end of a lever 77 which is fulcrumed by means of a shoulder screw 77" freely entering the bearing aperture 78 in the disk 64. cavity 79 for the coil spring 80, the opposite ends of which are anchored, respectively, to the disk 64 and lever 7 7. The spring 80 yieldingly holds the jaw 77 in contact with the fixed jaw 76, as shown in Figs. 5, 9 and 22.

The lower end "ofwthe lever 7 7 is formed with a, notch defining a vertical edge 81 which is adapted to be engaged by the pin 82 on the latch-lever 83 fulcrumed at 84 in the slot 85 in-the bracket 66. The lower end of the latch-lever 83 ,is notched at 86 to tilted about its fulcrum 90- from sewing po-' sition, shown in full lines, Fig. 4, to open or dotted line position, for removal of the bobbin-case from the hook 35. The described movement of the latch-lever 83 also carries its pin 82 against the edge 81 of the movable j aw-carryin lever 77 and forcibly shifts the movable aw 77 away from the fixed jaw 76 causing a relative expansion of said jaws and the consequent gripping of the bobbin-case which is forcibly removed from the hook-cavity to the readily accessible position shown in dotted lines in Fig.

Surrounding the aperture 78 is the 4. This movement of the bobbin-case to a predetermined accessible osition pulls a, predetermined length of obbin-thread b from the bobbin which may be readily severed by the operator prior to picking up the bobbin-case from its then inclined support 66. The latch-lever. is yieldingly urged to locking position, Fig. 22, by means of the spring 91 which is disposed within the slot 85 and is coiled about the screw 92. The screw 92 also forms an adjustable stop for the stem 65 of the bobbin-case supporting disk 64 and assists in adjusting such disk to the correct operating position relative to the rotary hook.

The take-up is of the so-called link or crank-and-link operated type andcomprise's the usual angle-lever having rigidly related arm 93, 94, the former of which embraces the take up operating crank 7 and the latter of which is formed with the thread-eye 95. The lever 93, 94, is pivotally connected at the juncture of its arms to one end of the anchor link 96 the opposite end of which is pivoted at 97 to the lug 98 within the head The tension device 'is of common form and comprises the separate disks 99 which are yieldingly pressed together by the spring 100 upon the thread passing between them to frictionally retard the feed of such thread. The tension device also has associated therewith the usual light check-spring 101 which yields thread to the take-up as the latter completes its up-stroke after having drawn up the needle loop. The spring 101 also takes up the slack given up by the take-up eye in the down-stroke of the needle and prevents the formation of slack below the eye of the needle, particularly when sewing thin work. Fixed to the presser-bar is the arm 102 which extends under the check-spring 101 anddetermines-the lower limit of the movement of the latter in accordance with the thickness of the work.

Operation.

The loop is seized from the needle, spread and carried around the bobbin to cast off position, Fig. 22, in the usual manner; such loop passing easily through the gap then existing between the lifter-arm 71 and the.

shoulder on the bobbin-ease. The takeup now operates rapidly to draw up the loop; allowing but little slack in the loop as the latter follows the heel 42 in the u ward movement of the latter. The hanger anges 63, 63 of the bobbin-case rest upon the bobbin-ease supporting disk 64,and the lifterarm 71 which is spaced below the shoulder 70 on the bobbin-case approaches the latter as the feed-dog rises. When the hook reaches the position shown in Fig. 23, the

bobbin-case is just beginning to be lifted to I l' a gap e ween the hanger flanges 63,

63' and the bobbin-case supporting disk 64: The hook-point 36 is covered bythe guard flange 59 and the supply limb of the needleloop is still detained by the shoulder 55 and the wall of the hook-raceway 37. At a slightly later stage, Fig. 2/1, the shoulder 38 adjacent the oblique gap 39 in the hook passes the shoulder 55 and releases the supply limb of the needle-loop which immediately escapes upwardly through the oblique gap 35' to the position shown in Fig 24; 1t being remembered that, the take-up is rapidly pulling up on the supply limb of the loop at this time and the loop has not as yet been dislodged from the heel 42. The hookpoint 36 is still covered by the guard flange 59 and the supply limb of the needle-loop is further deflected upwardly as it is drawn in a straightaway course over the transversely convex surface 41 of thehook-beak and is thus carried well out of range of possible seizure by said hook 36. As the hook point passes loop-seizing position, the camedge 60 of the guard flange 59 dislodgesthe needle-loop from the heel 42 and by the time the loop is somewhat further reduced in size the feed-dog. has reached the limit of its lifting movement and the arm 71 has lifted the hanger ledges 63, 63 off of the supporting disk 64 to provide the gap for escape of the needle-loop. The work-limb of the loop now engages the loop-detaining horn 61, Fig. 26, while the supply limb passes through the gap between the jaws 76, 7 7 and the walls of the rotation-restraining notch .55 in the bobbin-case. Finally the loop slips upwardly off of the horn 61 and is drawn up to the work through the needle-hole in the throat plate 32. The take-u action does not start until the needle-eye as risen to a height of more than five-sixteenths of an inch above the throat-plate and the loop is taken up to the work, Fig. 30, before the needle starts down.

It will be noted in reference to Fig. 30 that although the needle-loop hasbeen taken up to the work, the take-up has not quite reached the limit of its up-stroke. The further upward movement of the take-up lifts the check spring to its upper limit, Fig. 31, and pulls through the tension device 99 an amount of thread equal to that used in making the precedingstitch. When sewing thicker work the arm 102 is elevated and lifts the spring 101 a corresponding amount, thus reducing the distance said spring will be lifted by the take-up. The take-up is thus caused to pull a greater amount of thread from the supply. By reference to Fig. 31 it will be seen that the take-up starts to give slack very early in the down-stroke of the needle so that slack thread is provided for doubling through the thickest work in the descent of the eye of the needle through the same, while retaining a minimum length of needle-stroke. So far as I am aware this desirable result has not heretofore been attained.

When renewing the lower thread mass, it is merely necessary to draw the bobbinthrea d end into the slot 57, thence under the spring 56 and thence into the slot 58. The

bobbin-case is then replaced upon its support 64 which is swung upwardly to vertical position. When the first needle-loop is cast around the bobbin-case it gathers in the bobbin-thread and automatically draws the bobbin-thread into position against the ledge 60 within the rotation-restraining notch 52. The bobbin-case tension device may be easily cleaned of lint during the act of threading the same, by merely drawing the thread past the notch 58 and toward the tension spring regulating screw 56", thus wiping the adjacent surfaces of the bobbin-case and tension spring free from lint.

Having thus set forth the nature of the 2. In a look-stitch sewing machine, in

combination, a rotary hook having an open raceway, a stationary bobbin-case support, a' bobbin-case disposed in said raceway and having an upper portion resting upon said support, a take-up, and a pivoted lever extending under and adapted to engage and,

lift said bobbin-case from its support during a predetermined period of each stitch forming cycle as the needle-loop is being drawn up to the work, to permit the escape of the needle-loop from the bobbin-case.

3. In a sewing machine, a reciprocating needle, a rotary book, a stationary bobbincase support, a bobbin-case resting upon said support, a bobbin-case lifter disposed below the bobbin-case, and means for mov ing said lifter to cause it to raise and lower the bobbin-case.

4. In a sewing machine, a reciprocatingneedle, a rotary hook, a stationary bobbincase support, a bobbin-case resting upon said support, a bobbin-case lifter disposed below the bobbin-case, and means for moving said lifter vertically.

5. In a sewing machine, a reciprocating needle, a rotary hook, a stationa bobbincase support, a bobbin-case restm u on said support, a feed-dog, means or 1132- engagement with the bobbin-case. and lift.

the latter from its support.

6. In a sewing machine, in combination,

a reciprocating needle, a cup-shaped rotary book, a bobbin-case support, a bobbin case restin on said support and received partially within said hook, said bobbin-case being formed at its lower side externally of the hook with a shoulder, and means adapted to, engage said shoulder and lift the bobbin-case from its support.

7. In a sewing machine, a reciprocating Jneedle, a rotary hook, a bobbin-case support, a bobbin-case, a feed-dog, afeed-dog lifting element, and a bobbin'oase lifting element mounted on said feed-dog lifting element.

8. In a sewing machine, a reciprocating needle, a rotary hook, a bobbin-case sup-' port, a bobbin-case, a feed-dog, a feed-dog ifting element, a bobbin-case lifting elementmounted on said feed-dog lifting element, and means for relatively adjusting said elements. j

9. In a sewing machine, a-reciprocating needle, 9. circularly moving hook, a bobbincase having a rotation-restraining notch, and rotating-restraining means entering said-notch, said bobbin-case being formed with a needle-loop detaining horn on that side of said'notch last passed by the hook in seizing a needle-loop.

10. In a sewing machine, a reciprocating -needle, a circularly moving hook, a bobbin-case having a rotation-restraining notch, and rotation-restraining means entering said notch, said bobbln-case being formed with a needle-loop detaining horn reduced in cross-section below its upper end and disposed on that side of said notch last passed by the hook in seizing a needle-loop. 11. In a sewing machine, a reciprocating needle, a circularly moving hook, a bobbincase support movable from sewing position adjacent said hook to open position more remote therefrom, a bobbin-case resting upon said support, and manually operating gripping means on said support for seizing the bobbin case and removing it from the field of action of said hook when the bobbin-case support is shifted, said means being out of gripping engagement with the bobbin-case when the machine is sewing.

12.. In a sewing machine, a rotary hook having an open raceway, a stationary bobbin-case support, a bobbin-case resting upon said support and having a notch, and ro-.

tating restraining means on said support entering the notch in said bobbin-case, said. means being expansible to grip the walls of said notch for removal of the bobbin-case from the rotary hook.

13. In a sewin machine, a reciprocating needle, a circular y moving hook, a bobbin- .case .support movable from sewing position adjacent said hook to open position more remote therefrom, a bobbin-case resting upon said support and having a notch, and relatively expansible gripper jaws mounted upon said support and entering said notch.

14. In a sewing machine, a reciprocating needle, a circularly moving hook, a bobbincase support movable from sewing position adjacent said hook to open position more remote therefrom, a bobbin-case resting upon said support, and manually operated means on said support for seizing the bobbin-case and removing it from said hook when the bobbin-case support is shifted.

15. In a sewing machine, a reciprocating needle, a circularly moving hook, a bobbincase support movable from sewing position adjacent said hook to open position more remote therefrom, a bobbin-case resting upon said support and havin a notch, a jaw fixed to said support an entering said notch, and a manually operated lever having a jaw disposed within said notch alongside said first-mentioned jaw.

16. In a sewing machine, a reciprocating needle, a circularly moving hook, a bobbincase support movable from sewing position adjacent said hook to open position more remote therefrom, a latch on said bobbincase support forlooking it in sewing position, a bobbin-case resting upon said support, and means actuated by the releasing movement of said latch for seizing said bobbin-case, whereby the latter may be caused to move with the bobbin-case support to open position.

17. A sewing machine bobbin-case comprising a one-piece cylindrical shell formed at its outer end with a rotation-restraining notch, a tension spring mounted externally upon said shell, said, shell having open-ended threading slots adapted to lead the bobbin-thread under said tension spring, oneof said slots being cut inwardly from the outer end of said cylindrical shell whereby the bobbin-thread may be led across the outer end of the bobbin-case to and through said which is formed with an oblique slot defining a loop-seizing beak, a bridge-plate crossing said slot and formed With a concave loop-deflecting edge leading to a loop-arresting heel, said hook-beak having an outer surface adjacent the concave edge of said bridge-plate which is conveXed transversely of said hook-beak.

20. A rotary hook for sewing machines comprising a cup-shaped body the rim of which is formed with an oblique slot defining a loop-seizing beak, a bridge-plate crossing said slot and formed with a concave loop-deflecting edge leadin to said looparresting heel, said hookak having a transversely convexed outer surface adacent and extending under the concave et ge of said bride-plate.

21. In a sewing machine, a rotary hook having an open' raceway, a stationary bobbin-case support, and a bobbin-case resting upon said support and formed with a rota: tion-restraining notch and with a peripheral flange adapted to guard the point of the hook as the latter is completing a loop-casting rotation, said flange terminating at said notch.

22. In a sewing machine, a rotary hook having an open raceway, a stationary bobbin-case support, and a cylindrical bobbincase resting upon said support, said bobbin- 7 case being formed at its outer end with a rotation-restraining notch and further at said end with a peripheral rib received in the open raceway of said hook, and still further at said end with a guard flange adapted to guard the point of the hook as the latter is completing a loop-casting rotation, said flange terminating at said notch.

In testimony whereof, I have signed my name to this specification.

' MARTIN HEMLEB." 

